The present invention is directed to apparatus for surface bonding and assembly means therefor in the tire body buildng art and particularly as concerns the relative traversing motion between rotating tire supporting struture and pressing or bending means.
When plastic component such as unvulcanized sheets of rubber or rubberized fabric are assembled as in the building of tires; it is frequently necessary to bring the tacky surfaces of said sheets into intimate contact and work out entrained air bubbles by rolling the surface with a narrow roller device commonly referred to as a stitcher. This process, known as stitching, is normally accomplished by a relative motion between the materials to be consolidated and the stitching wheel whereby said wheel is biased against the surface of the material to be consolidated thereby tracing a line of contact on the material. This line of contact is progressively advanced laterally of the material thereby tracing a series of relatively parallel contact lines that tend to consolidate the material and thus work any entrained air out toward the open edge over the material surface where said air may escape.
The stitching of material that is in certain geometric shapes such as planes or cylinders may be accomplished by a relatively simple apparatus. The stitching of the various components or sheets of material of a cylindrical assembly is normally accomplished by bringing a pair of stitcher wheels into contact with the longitudinal center of the work piece. The rotational axis of each stitching wheel being parallel to the longitudinal axis of the cylindrical work piece. The work piece is then rotated about its own axis and with each of the stitcher wheels being biased against the surface of said work piece, they are gradually advanced laterally and in opposite directions. The stitcher wheels in their movement tend to trace a helix pattern of contact on the work surface, thereby progressively urging the various components of material into intimate contact with one another and thus displacing entrained air bubbles to an open edge of the material. The stitching of the more complex surfaces, such as the toroidal shape (doughnut) of tire structures, requires that the sticher wheel be capable of maintaining an attitude preferably normal to the tangent of the cross section surface at the point of stitching contact.
In view of the three-directional force and motion requirements of a modern radial tire stitching apparatus, it has been determined that standard stitching equipment is not suitable nor acceptable. Furthermore it has been ascertained that stitchers which have been designed and developed to meet such multi-directional stitching requirements are both complicated and undesirable because of their complexity, inflexibility, and maintenance problems.